Jewelry and other adornments have been valued since antiquity. Initially, such items were likely made from carved animal bones or shells. Later, jewelry made from gems became highly valued as symbols of wealth and status and as mystical tokens for warding off evil spirits.
Gems are usually pieces of rock or mineral that are cut and polished to form jewelry or other adornment. While some gems are very rare and expensive, others are relatively common and are far less expensive. Furthermore, some gems are very hard, some are soft, some polish easily, others are far more difficult to polish. Some gems are faceted to produce optically pleasing effects while others are formed into cabochons to enhance visual attractiveness. As may be appreciated the art of forming gems into jewelry or other adornment is highly specialized.
One property in which gems differ greatly is their difficulty of fabricating. Some gems have few flaws and cleave cleanly, others have many minute structural flaws that cause the gem to shatter, crumble, or weirdly cleave when being worked. The more expensive the gem the more expensive a mistake becomes. One gem that is notoriously difficult to fabricate is the opal, a gem which occurs in Tertiary-age rhyolite flows. In particular, the African (Ethiopian) opal is particularly difficult to fabricate.
Opal creation began when rhyolite was extruded from within the Earth's crust. Sudden releases of pressure caused gases to separate from the fluid magma and to form large cavities and fractures. Hot water percolating through the silica-rich rhyolite took silica into solution, which filed the cavities and fractures. When the water evaporated silica-rich deposits formed. As this cycle repeated over and over again over a very long period of time the silica rich deposits formed opals, a substance that is as hard as glass.
The now-filled cavities containing opals are referred to as nodules. The rhyolite nodules are subsequently removed (mined) from the surrounding rock. Such nodules range from less than an inch to more than a foot in diameter. Opals found within the nodules are located in stratified fillings or closely-spaced layers. Removing opals from rhyolite nodules is difficult, particularly for the aforementioned African opal.
While an Opal in a rhyolite nodule is not particularly attractive, after proper processing a very striking and beautiful opal can result. Unfortunately, the geological process that produces opals causes such opals to having numerous fault lines that can produce unpredictable outcomes, such as high rates of breakage and stone waste, when being removed from the rhyolite nodule. Nonetheless, because of their beauty opals are highly valued and used extensively as jewelry and other adornments. But, because of the difficulty of removing an opal from a rhyolite nodule producing opals is a highly specialized skill.
Some other gems are also hard to fabricate, for example, Emeralds. In such instances an epoxy adhesive sold as OPTICON® Trademark No. 1,607,901 has been used to treat gems before and after cutting. One reason for this is that OPTICON fills fractures found in gemstones. This provides fracture “healing” in gems such as emeralds. After an emerald is cut and polished the optical properties of OPTICON can reduce the visibility of faults. It should be noted that this fracture healing and fault hiding is controversial within the jewelry business.
When OPTICON was tried on an African Opal before cutting it did not work. The African Opal was likely too dry and unstable for the filling properties of OPTICON to work successfully. In further tests it was determined that African Opals treated with OPTICON cracked far more than other similarly treated gems, including other opals. Consequently while OPTICON can be a valuable asset with other gems it is rarely used in the treatment of African and other opals.
Accordingly, there exists a need for a method of stabilizing opals, particularly African Opals, when being fabricated from a rhyolite nodule. There also exists a need for a method of stabilizing an opal in a manner that reduces or prevents fragmentation during fabrication. There also exists a further specific need for a method of stabilizing a complete non-cracked opal without fragmentation which further prevents fragmentation during cutting.